Flow control valve stuck closed??

It seems most times flo control valves get stuck open and then you have the zone too hot due to runaway heat. I am wondering if mine is stuck closed cause the radiant heat in that zone never reaches temperature (70 degrees) and thus the cirulator is always running. The other 4 zones upstairs with baseboards are working fine, pressure is at about 17lb. and boiler temp is at 180 degrees.

It seems that the hot water pipe going into this flow control valve is hot but the pipe out of it is not. I am very worried to try to open it manually since the valve is original 1961? If in fact its stuck closed, if I try to bleed this zone, would nothing come out of the purge valve located on the return since the flow control valve is closed?? Any input is greatly appreciated!!

Most zone valves have a manual override...it should be safe to open it. The valve could be open, and not circulating in that loop because of an air lock, though, and purging might solve the problem...the valve could be okay. But, I think I'd try to manually open it to see if that does anything before I tried to purge it.

Depending on the brand and type, it might just be the motor head, which is replaceable without changing the valve.

To purge, the valve would have to be open, either manually, or, it's possible it is already open if the thermostat is calling for heat, but not flowing because of an airlock. Some have an indicator that shows whether it is closed or open.

Not necessarily...it's probably a one-way valve, and therefore, there's a path for water the 'long' way around. The air generally rises to the highest point in the system, so by opening a bleed valve there, you should be able to get it out. Depends on where the bleed valves are, and if it isn't really stuck, but it's an air lock, it's probably working anyway, just can't push its way into that loop.

I tried opening the flo- control valve manually and the thing would not budge... I even loosed and even removed the packing nut, and still nothing. Gee.... its only 50 years old.
So I removed the Bell and Gossett 100 pump to inspect the impeller for my cause of no heat in that zone: Well, that was it. The metal impeller was totally shot. Just a follow-up for all my pals in cyberland...

Here are a few pics of the steel impeller I pulled out of that old Bell And Gossett pump. Based on the date code on the bearing assembly, it is from August 1961, which makes sense since the building was built in 1961. Who knows how long that zone had poor heat because this a rental and just got a complaint of poor heat a few weeks ago. As of today, I have 4 of 6 zones running Taco 007 circulators. I rather not think about all those loose pieces of rusted impller debris floating around my system.